1. Field of the Invention
The present invention relates to a motor driven, hybrid compressor for use in an air conditioner for vehicles, and more specifically, relates to a structure of the compressor for preventing leakage current.
2. Description of Related Art
In a motor driven compressor having a motor for driving a compression mechanism, a high-voltage motor frequently is used. Therefore, the structure between terminal portion of the motor and the motor housing or the compressor housing (e.g., the body portion of the compressor) is insulated for safety. A structure which does not leak current is desired. In such motor driven compressors, liquid refrigerant (i.e., the liquid state of refrigerant gas) and oil with high electric conductivity suspended in the liquid refrigerant are considered to be causes of leakage current. When the liquid refrigerant and the oil enter into the motor side of the compressor, there is the possibility of leakage current. In a known motor driven compressor, a terminal portion of the motor of the motor driven compressor is positioned within uppermost portion of the motor driven compressor. Nevertheless, when the liquid refrigerant is collected on the motor-side of the motor driven compressor, because the distance between the terminal portion and the liquid level may be relatively small, the terminal portion may become submerged in the liquid refrigerant, thereby causing leakage current.
A connecting portion between an external terminal for supplying electricity to the motor of the compressor and a wire end portion of a stator of the motor of the compressor may considered to leak current readily. In known motor driven compressors, no measures appear to have been taken against such leakage current. In order to maintain a high degree of insulation, a connecting portion, which is separated or isolated from the liquid refrigerant and oil, is required. Nevertheless, if the connecting portion and the liquid refrigerant are separated mechanically by a seal mechanism or the like, the internal structure of the compressor may become complicated, and assembly and manipulation of the connecting portion become remarkably difficult.
A hybrid compressor for use in an air conditioner for vehicles and capable of being driven by an engine of a vehicle (e.g., an internal combustion engine of a vehicle or an electric motor of a vehicle) or a motor (e.g., a motor contained within the housing of the compressor) is described in Japanese Utility Model No. 6-87678. A hybrid compressor also is disclosed in Japanese Patent Application Nos. JP A 2001-280630 (JP-A-2002-031664) This hybrid compressor comprises a first compression mechanism of a scroll-type, compressor which is driven exclusively by an engine of a vehicle (e.g., an internal combustion engine of a vehicle or an electric motor of a vehicle) and a second compression mechanism of a scroll-type compressor, which is driven exclusively by a motor contained within the housing of the hybrid compressor. The fixed scrolls of each of the first and second compression mechanism are disposed back-to-back, e.g., extend in opposite directions from a common or shared valve plate, and are integrally formed with each other. In such a hybrid compressor, because the first compression mechanism and the second compression mechanism are driven selectively or simultaneously, improved compressor efficiency may be obtained.
Nevertheless, the hybrid compressor contains the motor, and a liquid refrigerant may enter into the second compression mechanism (i.e., the motor driven compression mechanism). In such a hybrid compressor, high electric conductivity is required to deliver electricity to operate the motor driven compression mechanism. When the amount of liquid refrigerant is increased in the motor driven compression mechanism, leakage current may occur readily.